The invention relates to energy cells containing certain chalcogen halide compounds as ionic conduction components and a process for the manufacture thereof.
So-called solid electrolytes are already known, and new types of batteries and fuel cells have been built or have been proposed utilizing such electrolytes. These solid electrolytes are also called super-ionic conductors or optimized ionic conductors. The known ionic conductors are divided into three groups according to "J. Solid State Chemistry" 4, 294, 310 (1972), i.e., 1. Ionic compounds that are characterized by a disordered cationic phase, as for example in the silver halides and silver chalcogenides. 2. The isomorphous series of hexagonal compounds with the so-called beta-aluminum oxide structure. 3. Defect-stabilized ceramic oxides with the calcium fluorite structure.
The possibility of using these ionic conductors in energy cells rests upon the postulate that in all cases a very slight electronic conductivity is combined with a high ionic conductivity. The use of these ionic conductors in an energy cell, as for example, a so-called ionic battery or a galvanic cell, is accomplished by using the actual ionic conductor to separate the various electrode materials that supply the driving force for the electrochemical reaction. By so doing, the ionic conductor as "solid electrolyte" replaces the electrolytic solutions that have heretofore been customary, and eliminates the problems that arise from the presence of a liquid phase. As to the heretofore-known energy cells including solid electrolytes, such solid electrolytes have been used only in conjunction with liquid electrodes.
In energy cells with ionic conductors or solid electrolytes, the electrode materials can consist of solids, liquids or gases. For the attainment of a substantial electro-motive force, the solid electrolytes should consist of at least one electro-positive and one electro-negative material.
Previously-known energy cells with solid electrolytes or ionic conductors despite their great theoretical possibilities, still shown many disadvantages, and these disadvantages have impeded their technical utilization, e.g., the electro-chemical reaction at the boundary surfaces of the solid electrolytes leading to serious corrosion problems. A further drawback with respect to ionic conductors as encountered in previously known galvanic cells, is the fact that the ionic conductivity becomes adequate for carrying out electrochemical reactions only at temperatures above 150.degree. C and up to about 350.degree. C, (cf. J. Phys. Chem. Solids, 34, 1199 (1974)).
Further disadvantages are the often very high prices for many of the materials, and the exceedingly high weight in the case of other materials.